Transcritical Refrigeration With Pressure Addition Relief Valve

Abstract

A refrigeration system ( 20 ) includes a pressure addition relief valve ( 62 ) in parallel with an expansion device ( 63 ).

1 . A cooler system comprising:
 a compressor ( 22 ) for driving a refrigerant along a flow path in at least a first mode of system operation;   a first heat exchanger ( 24 ) along the flow path downstream of the compressor in the first mode so as to act as a gas cooler;   a second heat exchanger ( 28 ) along the flow path upstream of the compressor in the first mode so as to act as an evaporator to cool contents of an interior volume of the system;   an expansion device ( 63 ) in the flow path downstream of the first heat exchanger ( 24 ) and upstream of the second heat exchanger ( 28 ); and   a pressure addition relief valve ( 62 ) in parallel with the expansion device.   
   
   
       2 . The system of  claim 1  wherein:
 the pressure addition relief valve ( 62 ) is a purely mechanical valve.   
   
   
       3 . The system of  claim 1  wherein:
 the expansion device ( 63 ) is a purely mechanical device.   
   
   
       4 . The system of  claim 1  wherein:
 the pressure addition relief valve ( 62 ) is normally closed and configured to open responsive to a combined force produced by pressures essentially respectively immediately downstream of the first heat exchanger and upstream of the second heat exchanger.   
   
   
       5 . The system of  claim 4  wherein:
 a bias force acts opposite the combined force, the bias force comprising at least one of:
 a supplemental spring ( 94 ) bias force; 
 a bias force provided by a system condition sensor ( 110 ); and 
 a bias force exerted by ambient air pressure. 
   
   
   
       6 . The system of  claim 1  wherein:
 the pressure addition relief valve ( 62 ) is integral with the expansion device ( 63 ).   
   
   
       7 . The system of  claim 1  wherein:
 the expansion device ( 63 ) comprises a fixed orifice ( 120 ) in a common body ( 70 ) of the pressure addition relief valve.   
   
   
       8 . The system of  claim 1  wherein:
 the expansion device ( 63 ) comprises non-EEV device.   
   
   
       9 . The system of  claim 1  wherein:
 the pressure addition relief valve comprises a sheet metal spring membrane ( 84 ) and no other spring.   
   
   
       10 . The system of  claim 1  wherein:
 the pressure addition relief valve comprises a membrane ( 84 ) and a coil biasing spring ( 94 ).   
   
   
       11 . The system of  claim 1  wherein:
 flowpath portions upstream ( 76 ) and downstream ( 78 ) of the expansion device have effective counterbias areas of the pressure addition relief valve, the lesser being no less than 10% of the greater.   
   
   
       12 . The system of  claim 1  being a self-contained externally electrically powered beverage cooler positioned outdoors. 
   
   
       13 . The system of  claim 1  wherein:
 the refrigerant comprises, in major mass part, CO 2 ; and   the first and second heat exchangers are refrigerant-air heat exchangers.   
   
   
       14 . The system of  claim 1  wherein:
 the refrigerant consists essentially of CO 2 ; and   the first ( 24 ) and second ( 28 ) heat exchangers are refrigerant-air heat exchangers each having an associated fan ( 30 ;  32 ), an air flow across the first heat exchanger being an external to external flow and an airflow across the second heat exchanger being a recirculating internal flow.   
   
   
       15 . The system of  claim 1  in combination with said contents which include:
 a plurality of beverage containers in a 0.3-4.0 liter size range.   
   
   
       16 . The system of  claim 15  being selected from the group consisting of:
 a cash-operated vending machine;   a transparent door front, closed back, display case; and   a top access cooler chest.   
   
   
       17 . A transcritical CO 2  refrigeration system comprising:
 a compressor ( 22 ) for driving a refrigerant along a flow path in at least a first mode of system operation;   a first heat exchanger ( 24 ) along the flow path downstream of the compressor in the first mode so as to act as a gas cooler;   a second heat exchanger ( 28 ) along the flow path upstream of the compressor in the first mode so as to act as an evaporator;   an expansion device ( 63 ) in the flow path downstream of the first heat exchanger ( 24 ) and upstream of the second heat exchanger ( 28 ); and   a pressure addition relief valve ( 62 ) in parallel with the expansion device.   
   
   
       18 . A method for operating a transcritical CO 2  refrigeration system comprising:
 compressing and driving a refrigerant along a flow path in at least a first mode of system operation;   cooling the compressed refrigerant along the flow path downstream of the compressing;   expanding the cooled refrigerant; and   heating the expanded refrigerant;   
     wherein:
 the expanding comprises a mechanically automated varying of an effective flow restriction based upon an additive combination of forces from pressures respectively upstream and downstream of the restriction. 
 
   
   
       19 . A method for remanufacturing a transcritical CO 2  refrigeration system or reengineering a configuration thereof wherein a baseline configuration comprises:
 a compressor ( 22 ) for driving a refrigerant along a flow path in at least a first mode of system operation;   a first heat exchanger ( 24 ) along the flow path downstream of the compressor in the first mode so as to act as a gas cooler;   a second heat exchanger ( 28 ) along the flow path upstream of the compressor in the first mode so as to act as an evaporator; and   an expansion device ( 26 ) in the flow path downstream of the first heat exchanger ( 24 ) and upstream of the second heat exchanger ( 28 ),   
     the method comprising at least one of:
 adding a pressure addition relief valve ( 62 ) in parallel with the expansion device ( 26 ); and 
 replacing the expansion device ( 26 ) with a pressure addition relief valve ( 62 ) and a structurally different expansion device ( 63 ).